Excavators are heavy earthmoving construction equipment. Excavators are generally comprised of a frame with tracks or wheels, an operator's cabin that is mounted on the top of the frame, a digging arm which consists of a boom portion and a stick portion, and a digging bucket attached to the stick portion of the digging arm. Both the operator's cabin and the digging arm are able to rotate 360° in a horizontal plane. The movements of the various components of the excavator are controlled through the use of hydraulic rams and hydraulic fluid.
Excavators have the function of digging into the earth. An operator's cabin and digging arm are mounted on a rotatable base. A counterweight is also mounted on the rotatable base. The rotatable base is mounted onto a self-propelled mobile (wheels or track system) frame. While the operator's cabin and the digging arm are capable of revolving 360° in a horizontal plane, neither are capable of moving forward or backward independently of the underlying frame (chassis) of the excavator.